1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly to a semiconductor device using a silicide and a manufacturing method thereof.
2. Description of the Related Art
In a recent miniaturized semiconductor device, especially in a metal insulator semiconductor (MIS) type field effect transistor (FET) device, it has been demanded to improve characteristics of the semiconductor device, such as an increase in a speed and a reduction in power consumption. In order to increase the speed of the semiconductor device, it is required to improve a current driving force of an active component. In a conventional semiconductor device, the current driving force has been improved with a reduction in a gate length. However, a sufficient improvement in the current driving force cannot be expected by a simple reduction in the gate length with progress of miniaturization in recent years. Therefore, improving the current driving force by any alternative technique has been demanded, and there has been used, e.g., a technique which gives a stress to a channel region of an FET to enhance mobility of a carrier.
In a complimentary metal oxide semiconductor (CMOS) device, there has been known that a current driving force of the semiconductor device can be improved by applying stresses with opposite direction to respective channel regions in an n channel MOSFET (which will be referred to as an nMOS hereinafter) and a p channel MOSFET (which will be referred to as a pMOS hereinafter).
In a conventional CMOS semiconductor device, a silicide is formed on a surface of a source/drain contact region of each of the NMOS and the pMOS to reduce a parasitic resistance of the active device. As the silicide, there is used, e.g., titanium silicide (TiSi2), cobalt silicide (CoSi2), nickel silicide (NiSi) or the like. It is known that these silicides all have a tensile internal stress against silicon.
If this type of silicide is formed on the surface of the source/drain contact region of the MOSFET, a compressive stress is induced in the source and the drain (in the silicon substrate) immediately below the silicide, and a tensile stress is induced in the channel region of the MOSFET arranged beside the silicide. When the tensile stress is given to the channel region, in the nMOS, mobility of a carrier (electron) flowing through the channel enhances, which contributes to an improvement in a current driving force. However, in the pMOS, since a carrier flowing through the channel is a hole, and thus its mobility reduces. Accordingly, there arises a problem that a driving current is decreased in the pMOS. In order to enhance the mobility of the hole, a compressive stress must be applied to the channel of the pMOS.
Therefore, an improvement in the current driving force can be realized by giving a tensile stress to the channel region of the nMOS and the opposite compressive stress to that of the pMOS.
In a conventional salicide technology used to form a silicide, a direction of a stress induced in a silicon substrate is uniquely defined depending on a kind of silicide to be used. Therefore, if only one kind of silicide is used, a current driving force of one of the nMOS and the pMOS can be improved, but a current driving force of the remaining one is disadvantageously lowered. If a dual silicide structure using two kinds of silicides is adopted, stresses in desired directions can be given to both the nMOS and the pMOS, but there is another problem that a manufacturing process becomes very complicated.
In order to solve the problem, Jpn. Pat. Appln. KOKAI Publication No. 2003-60076 discloses a technology in which one type of silicide is formed in a source and a drain, then a first silicon nitride film (an Si3N4 film) having a tensile stress is formed on an nMOS region and a second Si3N4 film having a compressive stress is formed on a pMOS region. These Si3N4 films control the stresses induced in the nMOS and pMOS channel regions in opposite directions each other, thereby improving respective current driving forces. Since the first and second Si3N4 films are formed by different manufacturing methods, the manufacturing process becomes complicated. Further, there occurs a new problem, e.g., a problem of a stress in an interface region where the first and second Si3N4 films come into contact with each other.